1. Field of the Invention
The disclosed embodiments of the present invention relate to an input system for receiving a user input, and more particularly, to an input system utilizing a connection link for transmitting an electrical signal to a stylus pen, wherein the electrical signal is coupled to a touch panel via the stylus pen.
2. Description of the Prior Art
A conventional capacitive stylus pen has a large nib contact area to touch a touch panel that utilizes an indium tin oxide (ITO) pattern so the contact position can be determined correctly. Please refer to FIG. 1, which is a diagram illustrating an input system 100 utilizing a capacitive stylus pen 110 having a small nib contact area NS1. An ITO pattern with diamond-shaped electrodes is shown on a touch panel 120, and a plurality of traces X1-X5 and Y1-Y5 are arranged to sense a plurality of electrode columns and a plurality of electrode rows for obtaining horizontal and vertical position information of the capacitive stylus pen 110, respectively.
As shown in FIG. 1, the capacitive stylus pen 110 only touches the touch panel 120 at an electrode E33, which is one of the electrode columns corresponding to the trace X4, and is between two electrode rows corresponding to the traces Y3 and Y4. Please refer to FIG. 2A, which is a diagram illustrating charges induced by the capacitive stylus pen 110 and to FIG. 2B which is a diagram illustrating charges induced by another capacitive stylus pen 210 near the electrode E33, wherein the capacitive stylus pen 210 has a larger nib contact area NS2 compared to the nib contact area NS1. As shown in FIG. 2A, in a case where a sensing mode is self-capacitance sensing, an induced charge Q1 is sensed on the trace X3, while few induced charges are sensed on the traces Y3 and Y4 due to the small nib contact area NS1. Only the X-axis coordinate of the capacitive stylus pen 110 is obtained, and therefore the capacitive stylus pen 110 cannot be positioned correctly. As a person skilled in the art can understand that the same problem exists for a mutual-capacitance sensing mode, further description is omitted.
One conventional method to solve the above problem is to increase a contact area of a capacitive stylus pen. Please refer to FIG. 2B again. Due to the larger nib contact area NS2, more induced charges are sensed on the trace X4, the traces Y3, and the trace Y4, which enables the capacitive stylus pen 210 to be positioned correctly, i.e., the contact position can be determined correctly. As a real pen usually has a sharp nib, however, a user would have a more real writing experience when using the capacitive stylus pen 110. There is therefore a need for an innovative input system which can provide the user with a more natural writing experience without degrading the positioning performance when a capacitive stylus pen with a small nib contact area is used.